1. Field of the Invention
This invention relates to a method for producing an ink jet recording head, particularly to a method for producing an ink jet recording head for generation of small droplets of ink to be used for an ink jet recording system.
2. Description of the Prior Art
Ink jet recording heads to be applied for ink jet recording systems are generally provided with minute ink discharging outlets (orifices), ink pathways and an ink discharging energy acting portion provided at a part of the ink pathways as the portion where the energy for discharging ink through the above discharging outlets acts on the ink existing in the ink pathways (energy acting portion).
In the prior art, as the method for preparing such ink jet recording heads, there is known, for example, the method in which minute grooves are formed on a plate of glass or metal by cutting or etching and then the plate having formed grooves is bonded with an appropriate plate to form ink pathways.
However, in the head prepared by such a method of the prior art, the internal walls of the ink pathways may be too coarse when formed by cutting or may be distorted due to the difference in etching degree, whereby ink pathways with good precision are hard to obtain and the ink jet recording heads after preparation are liable to give ink discharging characteristics which are scattered. Also, during cutting work, chipping or cracking of the plate is liable to occur to give a disadvantageously poor yield of product. And, when etching working is applied, it involves a large number of production steps which brings about a disadvantageous increase in cost. Another drawback common in these preparation methods of the prior art is that, during lamination of an engraved plate having formed ink pathway grooves and a lid plate having formed thereon of driving elements, such as piezoelectric elements or heat generating elements for generating energies acting on ink, it is difficult to effect registration therebetween with good precision, thus failing to afford bulk production.
As the method for producing ink jet recording heads which can overcome these drawbacks, there has been proposed a method for production of ink jet heads in which ink pathway walls comprising a cured film of a photosensitive resin are formed, as disclosed in Japanese Laid-open Patent Application No. 43876/1982. According to this method, ink-flow pathways can be minutely worked precisely and with a good yield. In addition, since this method provides for bulk production to provide ink jet heads at low cost, it can be said to be an excellent method.
However, although the ink jet head provided by such an improved method overcomes the drawbacks in the ink jet recording head of the prior art, the adhesive force between the substrate and the hardened photosensitive resin film is lowered during prolonged immersion in an ink, thereby forming minute peel-offs which have an influence on the characteristics of the ink, namely the precision of shot spots of the ink. This has been a great obstacle in recent years where the ink jet recording system is required to give an image quality of high resolution by means of a high density nozzle.